The Herschel Space Observatory is the fourth cornerstone mission in the
ESA science "Horizon 2000" plan

The Herschel Space Observatory is the fourth
cornerstone mission in the ESA science "Horizon 2000" plan. It will
carry a 3.5 meter passively cooled telescope, and will perform imaging
photometry and spectrometry in the far-infrared and submillimetre part of the
spectrum, covering approximately the 60-670 micrometres range. The science
payload consists of three instruments which will be provided by consortia led
by Principal Investigators: The Heterodyne Instrument for the Far-Infrared,
HIFI, whose PI is Th. de Graauw, SRON, Groningen, The Netherlands; the
Photodetector Array Camera and Spectrometer, PACS, whose PI is A. Poglitsch,
MPE, Garching, Germany; and the Spectral and Photometric Imaging REceiver,
SPIRE, whose PI is M. Griffin, Cardiff University, UK. Herschel is the first
space facility dedicated to the submillimetre and far-infrared, and will be
operated as a multi-user astronomical observatory that will provide observation
opportunities to the entire astronomical community. The launch is scheduled for
the first quarter of 2007.

The Herschel Space Observatory wavelength
coverage and unprecedented sensitivity, make the calibration of the instruments
particularly challenging. In this partially unexplored spectral range, the
photometry and spectral energy distributions of astronomical calibration
sources are derived from a combination of space and ground observations with
theoretical or semi-empirical models. Providing the Herschel mission with
suitable and well understood calibration sources will ensure the mission's
accuracy and scientific validity.

The main purpose of the workshop is to provide
an overview of the state of the art of models, observations and laboratory
spectroscopic studies associated with Herschel calibration sources, and to
facilitate the discussion between experts. The workshop will bring together
Herschel calibration scientists, modellers, observers, and calibration
scientists from other observatories that cover similar wavelength regions.
Theoreticians and observers will be given an insight into the Herschel
calibration requirements and into the areas that need further preparatory work.
Likewise, calibration scientists will obtain useful information for the
preparation of the instrument calibration plans. The output of the workshop will
be a compilation in the form of viewgraphs and articles, and a summary report
which will include a concrete plan for future collaborations. It is clear that
such an effort will be beneficial not only to Herschel, but also to other
present and future observatories in the far-infrared and submillimetre part of
the spectrum (e.g SOFIA, ALMA).

The meeting is organized and led by the
Herschel Calibration Steering Group. Contact people are: